Touch Panel Complementary Electrode Parasitic Capacitance Cancellation
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Solution Overview
Problem
Conventional touch panels face issues with detection accuracy due to electrical changes canceling each other out when objects come into contact with the same line in different regions, leading to glitches like non-detection, especially at slower sensing speeds.
Innovation Solution
A touch panel configuration that includes driver electrodes and detection electrodes, with a complementary electrode disposed along the driver electrode direction to form a parasitic capacitance component unaffected by object presence, and applying a complementary signal with a reverse phase to minimize inactive charge and prevent cancellation of electrical changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If parallel scanning is performed in multiple regions with 180° phase difference, then detection speed is improved, but electrical changes cancel out when objects contact the same line in different regions
Solution Approach 1:
A complementary electrode is introduced as an intermediary element to form parasitic capacitance that counteracts the cancellation effect. The complementary electrode receives a complementary signal that is 180° out of phase with the drive signal, creating an opposing electrical change that compensates for the cancellation caused by parallel scanning in multiple regions.
Solution Approach 2:
The invention changes the electrical parameters by introducing a complementary signal with reversed phase (180° difference) to the complementary electrode. This parameter change allows the system to maintain the high-speed parallel scanning capability while preventing the cancellation of electrical changes through constructive interference of the complementary signal.
2Length of stationary object
If detection electrode doubles as display electrode, then device thickness is reduced, but detection driving frequency cannot be freely changed due to display driving frequency restrictions
Solution Approach 1:
The invention segments the electrode functions by introducing a separate complementary electrode that is dedicated to touch detection functionality. This segmentation allows the display electrode to maintain its display function while the complementary electrode provides additional detection capability, enabling independent optimization of detection driving frequency without being constrained by display driving frequency requirements.
3Productivity
If active sensing speed is slow or multiple unit output changes accumulate, then glitches such as non-detection may occur
Solution Approach 1:
The complementary electrode provides beforehand cushioning by pre-establishing a reference electrical state that compensates for potential detection failures. When objects contact the detection surface, the complementary signal ensures that electrical changes are maintained above the detection threshold, preventing glitches such as non-detection even when sensing speed is slow or multiple unit output changes accumulate.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration ensures reliable detection without glitches, even when objects are in contact on the same line, by canceling out inactive charge and maintaining detection accuracy across varying sensing speeds.
Implementation Method 1
the complementary electrode forming along with the detection electrodes a capacitance substantially corresponding to a capacitance component that is not affected by a presence or absence of the object among capacitances formed between the driver electrodes and the detection electrodes
Data Source
AI summary
The touch panel (1a) of the present invention includes a plurality of driver electrodes (2), a plurality of detection electrodes (3) that extend in the column direction, and a complementary electrode (4), which extends in the direction in which the driver electrodes extend, and which forms a parasitic capacitance that corresponds to capacitance components that are not affected during detection of an object to be detected that comes into contact with or approaches the detection surface among the parasitic capacitances formed in the gaps between the driver electrodes (2) and the detection electrodes (3), in the gap from the detection electrodes (3).